Association between Air Pollution and Multiple Respiratory Hospitalizations among the Elderly in Vancouver, Canada

Abstract

Recurrent events, such as repeated hospital admissions for the same health outcome, occur frequently in environmental health studies. In this study, we conducted an analysis of data on repeated respiratory hospitalizations among the elderly in Vancouver, Canada, for the period of June 1, 1995, to March 31, 1999, using a new method proposed by () for recurrent events, and compared it with some traditional methods. In particular, we assessed the impact of ambient gaseous (SO₂, NO₂, CO, and O₃) and particulate pollutants (PM₁₀, PM_2.5, and PM_10–2.5) as well as the coefficient of haze (CoH) on recurrent respiratory hospital admissions. Using the new procedure, significant associations were found between admissions and 3-day, 5-day, and 7-day moving averages of the ambient SO₂ concentrations, with the strongest association observed at the 7-day lag (RR = 1.044, 95% CI: 1.018–1.070). We also found PM_10–2.5 for 3-day and 5-day lag to be significant, with the strongest association at 5-day lag (RR = 1.020, 95% CI: 1.001–1.039). No significant associations with admission were found with current day exposure.